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In children with Congenital Heart Disease (CHD) the responsiveness of the cardiovascular system to catecholamines differs intra- and interindividually to a great extent. Since this might be

due to a dysfunction of the adrenergic system the following investigations were carried out in 18 infants with and without cyanotic CHD. Tissue from the right cardiac auricle was taken

during heart surgery. Radioligand studies, using 125-I-Cyanopindolol were carried out on these tissues to estimate the density and affinity of the β-adrenoceptors (β-R). The proportion of

β1- and β2-receptors was determined by means of displacement curves using selective β1- and β2-antagonists.

1.) The average β-R density was lower in infants with cyanotic CHD than in those without cyanosis. The ratio of β1 - and β2-R appeared to be identical in both groups. 2.) Excessive release

of noradrenalin, and even more so of adrenalin, was found. These catecholamine levels were ten times higher than in controls. Infants with cyanotic CHD had significantly higher levels

compared to those suffering from CHD without cyanosis.

3.) A linear correlation was found between catecholamine levels and β-R density.

The conclusion can be drawn that infants with CHD have an increased activation of the sympathetic nervous system. The long-term exposition of myocardial β-R to catecholamines evidently leads

to receptor desensitization.

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